In The Classroom: Headspace Part 4

by Bob Dunlap and Ken BrooksDunlapkenBrooks
AGI Instructors and Master Gunsmiths

In Part 4 of this comprehensive look at headspace, Bob and Ken now test the effects of excessive headspace in their Mauser using commercial ammo. Previously their test using thicker military ammo failed to get the result they were looking for.

Spoiler alert: there will be a Part 5 coming soon where they use a higher pressure 30-06 cartridge in the hopes of getting the result they want!


5 Responses to In The Classroom: Headspace Part 4

  1. Is the protruding primer usually caused by excessive headspace. I have a Winchester .32 spcl. and the primers are always protruding out of the case now when fired….this happened after firing 3 rounds of the Hornady LEVERevolution ammunition they came out with. This ammo is loaded very hot!

    • If there is absolutely no headspace, the primer isn’t going to move. But even with a little headspace, which is more common, the primer will always back out of it’s seat the limit of the headspace. Then the pressure that builds up in the chamber will force the case back and reseat the primer flush. If the cartridge has a light pressure load however, the case will expand and grip the walls of the chamber and there may be insufficient pressure to overcome that friction and force the case back to the breech face. That may also be exacerbated by a rough chamber that really grips the brass.

      I spoke to Ken just this morning on the phone about this. His main point is that headspace is not the bugaboo people think it is–he told me that he has shot guns with .040″ headspace from the shoulder with no damage. It is usually excessive pressure, not headspace, that blows guns up.

      Note: I’m not the expert on this that Ken and Bob are, so opinions may vary.

  2. You know what my take on all this is? [Realizing, of course, that there’s still a Part 5 to come.] Here you have Bob & Ken–both experts in the field, far and above your average gunsmith–going out of their way to INTENTIONALLY cause a headspace separation, and they can’t do it! That tells me there is waaaay too much emphasis/importance given to headspace in the industry. [Knock on wood…!] Let’s just shoot and have fun; but keep our eyes open for obvious signs of problems along the way.

  3. I have a couple of (related) concerns. In stead of your own arm supporting the forearm of the rifle, wouldn’t you be better off using something like the “Lead Sled?” – Less chance of you hurting your arm.
    Next: Years ago, I bought my first 7mm Mauser (Mod 1893) and had lots of fun with it. That is, until one day using old military ammo, the gun recoiled more than it should have. When I looked at the bolt, I saw that the cocking piece was actually blown back past the “cocked” position. (These rounds were NOT reloads.) How does this read into head spacing, pressures, and gun failures?

    • I have a couple of (related) concerns. In stead of your own arm supporting the forearm of the rifle, wouldn’t you be better off using something like the “Lead Sled?” – Less chance of you hurting your arm.

      Robert,
      I think you hit the point exactly. If these two exceedingly experienced gunsmiths, who I am sure follow the safety code to a “T”, are willing to fire a high power rifle with 0.029″ of head space without anything but a cardboard shield? their point is made in my book. Big bad “head space monster” is not as scary as we are sometimes lead to believe! Have fun, Gerry

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